Double-checking molding press



July 1, 1947. w. STRAUSS 2,423,268

I DOUBLE-CHECKING MOLDING PRESS Filed March 25, 1945 3 Sheets-Sheet l M 6 v gwumkya WILLIRM STRAUSS Wow M July 1, 1947. Y I w, s uss Y 2,423,268

DOUBLE-CHECKING MOLDING PRESS Filed March 25, 1945 3 Sheets-Sheet 2 lllll WILLIA STRAUSS July 1, 1947. w. STRAUSS DOUBLE-CHECKING MOLDING PRESS 5 Sheets-Sheet 3 Filed March 25, 1945 3mm WILLIRM STRAUSS patente d July 1, 1947 DOUBLE-CHECKING MOLDING PRESS William Strauss, Bhiladelpliia, 'P-a assignor to F. .J. Stokes Machine Company, a corporation of Pennsylvania Applicationlwaroh zh 1945',"Seria-l No. 5.84363 (01. LQZ-l'25) 16 Claims. 1

Thisinvention relates to molding presses and it isooncernedespeoially with devices for checking the operation of automatic molding presses to stopthe'press in case of improper operation. This application is a .continuation-in-part of copending application, Serial Number 515;,967, filed December 28, 194%3.

An object of the invention is to devise acheeking device suitable for use on a multiple cavity molding press designed for general purpose mold.- ing. By the use of my invention, I am able to produce a itrlly automatic molding machine adapted for general purpose inoldin g and cape ble of a high production rate.

One of the problems sin-automatic molding machines which operate withoutatten'tion fireman operator is the danger-f mechanical injury to the machineadue tozdouble loading, thatis, where a molding charge is supplied to the cavity when the molded article previously formed has not beenproperly ejected from themachine. A further problem is to provide ior stoppage of the press when the supply of molding material becomesexhausted m'tis not properly suppliedto the cavities.

Various devices'have beendevisejd to checkithe operation of automatic .moldingpresses and stop the press in the event of certain improper conditions/ For example, checking arrangements have been devised in which the molded articles after being elected from the press are passed throughza Weighing device, and if the article is not of proper Weight, or if the propercnumher :of articles are not present after 'eachimolding cycle, the machine Will be stopped. Such arrangements give satisfactory operation where the :press is provided with only -a,..f8W cavities andlthe weighing device is sensitivexto:theabsence of vone oi" the molded articles. These arrangements, however, are not suificiently sensitive 1J0 sdetect themabsence of one article where thezpress is designed tozmold a large number of articles during each cycle, and are therefore not suitable for high production molding.

In molding special articles, such as -,s.c rew threaded caps, the-.checking'problem is not especially .difiicult, since the :molded article is not likely :to remainin the cavity, and it is necessary only to oheokthe force-.plugafter the unscrewing operation to be sure that no capremai-ns on the plugs duringthenext molding cycle.

In the case of a, molding press designed for general purpose work, that is, .in the case of a press designed totmold various forms ,of articles not necessarily involving screw threads or :other "projections on the mold parts which interlock here to thevfo-rce plugorpunch there., is.a..possibility that :somemay remain in the cavities and vice versa- In r e t bl e n roper heck ns of the operation of a genera-1 purposemolding .pressi have devised a-ch cki-ng de c 'Q- h cks the o e at u t e pr s tw ce dur n eachrmolding-cy that ehed Y ceehQ KS ach forc n e or munch imm a e y after op n-1 1 5 re the press and if a molded article is absent frorn I anyforce plug, the machine isstopped. The second checking operation takes place after theejectionef-lthe molded articles from theio-rce plugs, and if :a mold d rticle remain ranvr rce nlue-the-cperation-c the p esswi-l -.be-s tqpeedhe che ng dev ces c my ntent n involv ail-exploring device for exploring the article-car;- ry nsrpartroflthe m den steem-es evicecqm tro edhy t e exp i g device fo stop ing th press in t vent o simm red-ope ati n. The exploring device involves one oremore ,feeler elements w c explor the "mo iner a d c trol witchesr relays in a co danc w t the pre enee tor ab,sen ce of "a molded article. :Thereel r elements may he mec nica e er i mvin a tual c n act Wi hth m d d ic es 9r they may feel.o r sense-.ther articles'electrical-1y"w' h. utzphy e ontacte c d net i pre rred form o my invention nly n set o ee er e ements :isempl yed to p -f rm hat c cking eperations.

.MY iHVBHfiOK a o "invo v s no e a ran emen s vice and an ob ect of t e inv nt on s t -.r:.ed. s e to a min mum th numbe c m vin va q edif :t eQnerat omofl -nr s fin h-reletiv movement maybe o i fidfi z fi bymcving th art cle e r ng m d pa t :wi h res ec t t expl n d v ce, e -bkmovins thevexhlo n d ice with res ect t the :art clewarrxi g mold part.

Accordin t one orm of my in entionit 11s necesswvcmmw onl neim dplate-mini the press, whi e acco ding to, anot e -I rm, 'bq hiihe .l d.- ld-nlate ir meininvthei reseo d n -1v, i. .vent n p ovides a ieenete purp s m ldin ell- 3 11 3 a a l of is-h; P oduction-end-hevin fewer lmcv ng p ts and eingless subject to disorder ,than in the -.arrangements oithepriorart.

My invention is illustrated in the accompanying drawing in which:

Figure 1 is a side elevational view, partly in section, illustrating one form of exploring device mounted upon the movable die plate of a multiple cavity press;

Figure 2 is an enlarged vertical sectional view of one switch element of the exploring device;

Figure 3 is a diagrammatic view showing the electric connections for the checking device and the details of a special control relay forming part of the device;

Figure 4 is a side elevational view, partly in section, showing the exploring device mounted on a movable loading board or device of the press;

Figure 5 is a vertical side elevational View, partly in section, showing the exploring device mounted on the lower platen support of a moulding press in which the punch plate is mounted for movement outside of the press for ejection of the molded articles;

Figure 5a is a fragmentary side view of Figure 5 showing the manner of mounting the punch plate for sliding movement;

Figure 6 is a wiring diagram showing a modifled form of stopping device operated by the same type of exploring device used in Figure 3;

Figure 7 shows a modified arrangement using an electrical type of feeler element;

Figure 8 shows the details of mounting another type of exploring device which uses an electrical feeler element for one checking operation and a mechanical feeler for the second checking operation; and

Figure 9 is a view of Figure 8 taken along the line 99.

While my invention may be employed on a press operated by mechanical means, for the purpose of illustration I have shown the invention applied to a press operated by hydraulic means. Referring to Figure 1 of the drawing, the press selected for illustration comprises a base I having secured thereto four tension rods 2a, 2b, 2c and 2d extending upwardly and supporting at their upper ends a fixed cross head 3. A sliding crosshead 4 is guided for vertical movement by tension rods 2a to 2d and is supported on the upper end of a plunger 5 positioned in the hydraulic cylinder formed in base I. Sliding crosshead 4 carries a heated platen 6 which in turn supports a die plate I carrying a plurality of die elements 1a arranged in parallel rows and columns. An upper heated platen 8 is supported beneath fixed crosshead 3 by means of a pair of channel bars 3a and 3b suitably secured to the lower face of crosshead 3. A punch plate 9 is mounted on the lower face of platen 8 and is provided with a plurality' of punch elements ea arranged to cooperate with the die elements carried by the die plate I. Each punch element is provided with an ejecting pin I0, the pins being supported from a crosshead Illa carried by a vertically reciprocative rod IIlb passing through an aperture formed in crosshead 3 and being connected with piston I I of a hydraulic cylinder Ila mounted on top of the crosshead 3.

A bracket 4a secured to movable crosshead 4 forms an extension of the upper surface of heated platen 6 along which the die plate I may be moved from its operative position within the press into loading position beneath any suitable loading device I2 mounted above bracket 4a. Suitable guiding rails or bars 41; are arranged on opposite sides of die plate I and serve to guide the plate as it moves from one position to the other. Suitable hold-down strips 4b are secured to the rails 41) and extend over the lateral edges of the die plate 1. Any suitable means may be provided for shifting the plate I from its molding position to loading position and vice versa. In actual practice, this would be done by means of a hydraulic cylinder controlled by a suitable cycle controller, but the die plate may be moved manually. The operating arrangement has not been illustrated since it forms no part of the invention.

A suitable plate or tray I3 is hinged at one end to the front edge of die plate I and normally occupies the position shown in Figure 1 when plate I is in molding position. When the die plate is moved into loading position, tray I3 is drawn into the press and into a horizontal position beneath the punches So so that the articles which are ejected from the punches by ejecting pins II] will be deposited on the tray or plate. When the die plates moves back into the press, the article tray I3 moves into the inclined position shown in Figure 1 and the molded articles slide off of the tray and into a suitable receptacle not shown. The tray I3 is not essential and any other suitable means may be employed for removing the molded articles from the press after they have been ejected from the force plugs.

An exploring device is arranged to move with plate 6 and involves a horizontal bar I4 supported from the front edge of die plate I, any suitable supporting arrangement being employed to provide for vertical adjustment of the position of the bar. A plurality of checking switches I5 carried by bar I4, one switch being provided for each column of punches carried by the punch plate 9, and the row of switches carried by the bar I4 being parallel with the rows of punches. Each switch is operated by a suitable feeler element.

The checking switches are all alike, and one suitable arrangement is illustrated in Figure 2 which is an elevational view, partly in section, showing one switch element as viewed from the left of Figure 1. The switch structure embodies a suitable housing I5a preferably formed of insulating material and containing a pair of fixed upper contacts I51), I52) and a pair of lower contacts I50, I50. A movable contact I5d is carried on a plunger I5e and is arranged so that by reciprocation of the plunger contact I5d will bridge the upper pair of contacts or the lower pair of contacts. Plunger I5e carries at its upper end a yoke or bifurcated head I5 in which is pivotally supported a feeler wheel I5g. Plunger I5e and the attached elements are normally held in the upper position by any suitable biasing means such as spring I5h. The connections for the upper and lower pairs of contacts are shown extending out of the casing I5a on opposite sides of the switch unit. The bar I4 is initially adjusted so that the wheel I5g will not engage the punch 9a when the die plate is moved from loading position back to molding position, but when the die plate is moved from molding position to loading position at a time when the molded article I6 is carried by the punch 9a, the feeler wheel will engage the molded article and cause depression of plunger I5e and thereby shift movable contact I5d from its upper position to the lower position where it bridges the lower pair of contacts. It will be understood that all switches carried by bar I4 are operated substantially simultaneously under normal operating conditions when the switches pass a row of punch elements each carrying a molded article.

The checking switches are connected in -.a special control circuit diagrammatically represented: in Figure 3 for controlling -a power motor Mo which is the source of power for the pum-ps in thehydraulic system or, in the case of :a'mech air ically operated press, the motor Mo would drive the press operating-screws, cams or the like. The circuit of motor M is controlled by an electromagnetic switch A, theenergizing circuit of which is normally completed through normally closed contacts 130i 9, special relay torming part of the checking device of Figure 3. The checking relay involves a shaft C carrying a cam .13 arranged to open contacts B when the shaft is rotated through .a certain angle in a clockwise direction. The shaft isznormally urged in an anti-clockwise direction by a biasing spring D, and is rotated in aclockwise direction-by means of .a stepping magnet E which when energized operates a pawl P which .in turn engages and operates a ratchet G having two teeth. Two operations of the mag net E are required to rotate the shaft far enough to open the contacts B. "The shaft is held in its first operated position by means of a second ratchet wheel Hand a cooperating latch-P which may beudi-sen'gaged from the ratchet wheel H by releasing magnet M. A -suita'ble stop is provided in the path of cam .B" to :limitthe amount of backward rotation :of shaft C when pawl P is released.

'MagnetsEand-M are energized from a suitable supply circuit and are controlled by the checking switches 15 diagrammatically represented in Figure '3. As will be seen, the circuit of magnet E is completed through the upper pair of contacts of switches i connected in serial circuit relation, and the circuit of magnet M is completed through the :lower pairs of contacts of the switches connected in serial circuit relation. Magnet E is normally energized so that shaft .0 is normally ratcheted around -to its mid position and is held in this position by pawl P.

Operation-of Figures 1 to 3 is as follows:

It will he understood that the operation of the press .is controlled in any suitable manner, either manually orautomatically, to execute asuccession of molding cycles. automatically by suitable control means well known to those skilled in the art. As the lower die. plate is movedout of the press following the compression stage of the cycle, the checking switches pass underneath the successive rows of punches or force plugs arranged transversely of the'direction of movement of the die plate and parallel with the bar l4. It will be remembered that magnet E is normally energized and shaft C is held in its mid position by latch P. If all of the aswitchesare actuated downwardly by articles on the force plugs, then the circuitto magnet M will be completed and the pawl P will be withdrawn .from th ratchet H, and the shaft 0 will rotate back to its zero position. As soon as the switches move away from the first row of force plugs, they will all return to their upper position and'lm-agnet E will again be energized, stepping the shaft C around to its midposition. If one or more articles are not present in the next row of force plugs, one or more switches will not be operated to the lower position, and magnet M remains de-energized, and, as soon as the remaining switches are returned to their upper position, magnet E'is again energized and steps the shaft 0 around to a' position where it opens contacts 13 which deene'rg-izes the power motor and stops the press.

I prefer to control the press While the the plate is in loading "position charges of molding material are supplied to the cavities :inipl'ate :andtheejection piston I1 is operated to breakthe previously formed larlticles away from thepunches.

When the die plate 1 is moved back into the press, the operation of the checking switches will be the same as before except that the power motor will-bestopped if one 'or'more molded articles remain on the force plugs. For example, if one article sticks to one of the force plugs in the back row,one:of the checking switches will be operated to its lower positiomwhile the otherswitches will remain in their upper positions. 'Thiswill interrupit the circuit to magn'etE, but the circuit to releasingmagnet M remains open and the shaft C remains in 'i ts mid position. As soon as the single switch returns to its upper position, that is, assoon as -the checking switch moves away from the-backrow of the force plugs, the circuit to ma'gnetE is againcomple'tedand the shaft C iss-teppedaround to the position for openingconteeth and thus stops the power motor.

From the foregoin it will be seen that the checking relay'which controls the circuit ofpower switch A constitutes a storage device which requires-two consecutive operating impulses without an intervening releasin impulse in order to stop the press. So long as all checking switches are operated simultaneously, the checking "relay will be supplied-with alternate operating and releasing impulses, and the relay will never reach its finalpositionfor opening the circuit to the power motor. If, however, one or more switches areoperated when others are not, then two operating impulses will follow each other without an intervening releasing impulse, and the relay will be stepped around to a position to open the circult of switch A.

My invention contemplates any arrangement for alternately energizin magnets E and M by feeler devices which are operated by the molded articles carried on the punches when the die plate is 'moved-from molding position to loading position, the arrangement bein also effective to supply an additional impulse to magnet E when the die plate is moved from loading position into molding position if a molded article remains on any punch.

In Figure 4 I have shown the checkingswitch'es or feeler devices applied to a press of the type in which both the upper and lower platens remain within the press and a reciprocative loading board is employed to transfer preforms or charges of loading material from the loading device l2 to the cavities in the die plate I. In this arrangement, the parallel rails or bars ib mounted on bracket 4a serve to guide the movement-ofa loading board I! which is shifted by any suitable means from the position shown in Figure 4 into loading position under the loading device 12. The loading board H is of well known construction having a plurality of holes formed therein for receiving preforms or charges of molding material, the holes being arranged with the same spacing as the die cavities in plate I. A perforated feeding or bottom plate 18 is carried on the lower face of loading board ll and is-normaliy urged by suitable biasing means into a position where solid portions of the plate cover the holes in loading board l'l, hut when the board is moved towards the feeding position where the holes 'in the feeding plate are directly above the-cavities in the the plate, -a finger-or extension Ma on feedingplate l 8-engages the edge of the die plate or some other fixed part of the press and holds the feeding plate stationary while the loading board continues to move until it reaches the final position shown in Figure 4 when the preforms are deposited in the die cavities.

The bar I4 carrying checking switches I is mounted on a frame I'Ia secured to loading board Ill, and the checking switches operate as feeler devices for exploring the punches as the loading board moves from one position to the other and back again. The article receiving plate I3 is hinged to the front edge of loading board I1 and functions in the same manner as in Figure 1, except that during molding operation, the loading board I! and the plate I3 are withdrawn from the press to the right, the loading board resting beneath the loading device I2 and the plate I3 bein located between the loading device and the press. It will be understood that the loading device I2 is spaced from the press a distance suificient to accommodate the plate I3 and frame I'Ia so that switches I5 are positioned on the right of the press during the molding stage of the cycle. The frame I'Ia may serve to support the board I! for movement along rails (4b, and this frame also extends along the two sides and the front edge of plate I3. After the articles have been formed and the press opened, the loading board I1 is advanced until plate I3 is positioned below the punches. During this movement of frame IIa, the feeler devices I5 explore the punches for the presence of molded articles and if any are missing, the press will be stopped. When plate I3 comes into position below the punches, piston II is operated to dislodge the molded articles from the punches and deposit them on the plate I3, after which the loading board is moved further to the left and into the feeding position shown in Figure 4 where the molded articles are discharged from the plate I3, and the die cavities are refilled. When the loading board is withdrawn from the press, the feeler devices I5 check fo the absence of molded articles on the punches, and will stop the press if any are present, the operation being the same as described above in connection with Figures 1, 2 and 3.

In Figure 5 I have shown the checking switches applied to a molding press of the type wherein the upper platen carrying the punch plate is moved out of the press for ejection of the molded articles, and the checking switches are mounted on a, fixed part of the press. Elements corresponding to similar elements in Figures 1 to 3 are represented by the same reference char acters. In this arrangement the die plate I is mounted for movement out of the press and into loading position under the loading device I2 in the same manner as in Figure 1, although the die plate could remain in the press and a movable loading board like that shown in Figure 4 could be employed.

In Figure 5 the upper platen 8 carrying the punch plate 9 and ejector pins II] is mounted to be moved out of the press in a direction opposite to the direction of movement of the die plate I. For this purpose, the channel bars 30, and 3b are arranged parallel to the bars db, and a pair of guiding bars 3a'3b' are attached to the lower face of channel bars 3a3b and serve as lateral guides for platen 8. Suitable strips 3a."3b" are secured to the lower faces of bars 3a'-3b' and serve to support the platen 8 in its sliding movement. As shown in Figure 5, the

platen 8 and the attached elements are movable from the molding position shown in solid lines to the ejecting position shown in dotted lines, and vice versa.

The ejecting piston-cylinder combination II- IIa, instead of being mounted directly above the press is mounted on an extension 30 of crosshead 3, and the ejecting head Illa carrying ejecting pins II] is not carried by the piston rod Iflb, but is supported upon suitable biasing springs I00, and the upward movement is limited by the heads of suitable guiding bolts I. The lower end of piston rod I 8b is normally retracted out of the path of the ejecting head Ifla but is in position to operat the ejecting pins when the punch plate 9 is in the ejecting position shown in the dotted lines in Figure 5. A deflecting plate I3a may be provided immediately below the ejecting position of the punch plate for the purpose of deflecting the molded articles into a suitable container, but the deflecting plate may be omitted and the container may be placed immediately below the ejecting position of the punch plate.

The bar I4 carrying the checking switches I5 in Figure 5 is supported on suitable threaded rods Ida secured to movable crosshead i. The vertical position of bar I4 is adjusted so that with crosshead 5 in its open position, the checking switches are at the proper elevation to explore the punches carried by plate 9 as this plate moves from within the press to the ejecting position and from the ejecting position back into the press. On the outward movement .of the punch plate, the switches check the punches for the presence of a molded article on each punch, and on the return movement the switches check for the absence of molded articles on the punches.

In Figure 6 is shown a modified form of checking device which uses the same type of checking switch as in Figure 3 but does not use the same storage relay. In this arrangement, the check ing switches I5 are connected in series in the same manner as in Figure 3 except that the connections to the last switch in the series, instead of going to separate magnets, are connected to the winding of relay I9 which is of a slow-release type. Preferably, the time of release should be adjustable. The circuit through the winding of relay I9 is completed through contact Isa which is held closed by the relay armature 591; when the relay is energized. It will thus be seen that the energizing circuit of relay I9 may be completed by the switches I5 in either the upper position or the lower position of these switches, but all switches must occupy the same position. Also, if any one switch remains in a different position from another switch for a time interval longer than the time required for the release of relay I9, the energizing circuit of the relay will be opened and cannot be closed again except by operation of the push-button switch 20 which is arranged to bridge the contacts I9a-I9b of relay I9. The circuit of the main power switch A is completed through contact I on relay I9 when this relay is energized.

Operation of Figure 6 is as follows: The time delay in release of relay I9 is sufiiclently long so that the relay will not be released within the time required for the switches I5 to move from the upper position to the lower position, and vice versa. This will prevent release of relay I9 when all of the switches I5 are operated downwardly by acomplete set of articles in any given row. The relay will not be released when all switches are released and move upwardly simultaneously. If one or more articles should be. missing from the row, then th relay I9 willhave time to release its armature and the release of the relay causes release of power switch A, thus stopping the press. It will be understood that the rate of scanning the punches is adjusted so that the time required for the feeler wheel of achecking switch to. pass over a molded article is longer than the. delay period of relay I9. I prefer to use the microswitch type of switch for the checking switches l-in order to reduce the time required for movement of the switch element from one position to the other, although this type of switch is not essential.

In Figure 7 Ihave shown a modification in which the feeler elements do not havethe actual physical contact with the molded articles but constitute, electrical feelers which detect or, sense the presence'of a molded article electrically. In this arrangement the bar I4 is formed of insulating material and carries anumber of metallic feeler pieces 2|, one piece being provided, for eachcolumn of punches; and the bar Mis p0.- sitioned so that during relative movement of the bar with respect to the mold plate 9, the pieces 2| do1not come in. contact with the molded caps: t6 but pass beneath these caps with small clearance. Each feeler piece 2| and the corresponding punch 9a constitutes an electrical condenser, the capacity of. which isone valuewithout a cap on the punch; and. is of a greater value when. the cap is present due to the high dielectric constant of the molding'material from which the; caps are formed. This; change in value of the: condenserisutilizedto operate the checkingz switches; by connecting each condenser; in

circuitwith; a: source of alternating; current represented; by the transformer 22, and each circuit includes; a sensitive: amplifying. device 23 which; energizes a; relay 24 for operating the itch: 15. i

The operation. of; Figure; Z is: as follows; When thebar I14; is-displacedfrom the plate-9,; the relays 2.4. aredeenergizedi and the switches [35 are positioned. on their lower contacts. In this case the lower circuit of the switches 16%d5{.fl the stepping; magnet E1 of Figure 3. When the bar M is positioned beneath a row of punches having caps thereon, the increase inthe capacity oi the condenser elements: will cause operation; of the relays 2:1. tashiftwthe switches t5; tothe upper positions andoperate the releasing: magnet. Moi Figure 3. If any cap should be missing from one or more punchesinthe row, the corresponding relays will remain unoperated, and. the press will. be stopped. It is obvious that the arrangement of Figure 7 may be employed in the checking arrangement illustrated in Figure 6.

Figure 8'shows another form ofchecking device in which the punches are explored electrically on onechecking operation and are explored mechanically on the second checking operation. This figure showsthe arrangement for mounting one endof the; bar M. which carries the exploring elements, and the other end of the bar is provided with a. similar mounting arrangement. Figure 8 isa sectional View taken along the line 8-8 of Figure 9. The exploring device ismounted upon apair of rails: 25, only one of which is shown in FiguresB and 9. These rails are arranged on opposite sides of the lower mold plate, and in the case oi. Figure L. theywouldbe movable with the mold plate I. In the case of Figure 4 they would iorm apart of. the frame 1 1a, andin the case of 10 Figure. 5.-they wouldbe mounted on the crossheadJl. In allcases these rails would support the bar Min generally the same position as. inFigures- 1; 4 and 5..

Bar Hi ismounted uponthe-rails 25by means of: an interposed: wedge-shaped. camv piece 26 which is. thin at, the right end and. thick at the left end in- Figure 8. The bar [-4 is. maintained inposition on rails 25.103 means: of. a pair of pins 21. which are secured to the rails is-and. ex.- tendupwardlythroughholes formed in. the bar Id, These pins are provided with. nuts at the upper ends and suitable springs 28 arearranged onthe pins below. the nuts and servetoresiliently press-the bar l4 intc=contact with. the camv piece 26.

A- pair of vertical. standards. 29. are provided onthe; bar M at opposite ends thereof, and. a checking bar 30. is pivotally supported. on the standards by means. of trunnions 35a on. an axis passing throughv the lower edge thereof- The upper edge. on the. bar is relatively wide and. is provided with. aslotor groove in. which a. smaller metallic bar. 31. is insulatingly mounted by means of insulating material 301).

A circular cam. piece .32 is secured to, one, end of. trunnion 30a. and. isprovided with. a flattened upper portion 3.2a, this. cam piece being movable with. the checking; bar 3,0, about its pivotal axis. The bar 39. and theccam. piece- 32, are normally maintained. i the position. shown in. Figure. 8 by.- means. of. any suitable releasable latch represented by a spring: 33.having adetent which en.- gages. anotch. formed. in. the edge of cam, piece 32'. This arrangement is such that whena lateral force is exerted. on. the upper edge. of bar 3B, the bar may be tilted from itsnormalposition, and will remainin'the-tilted position by reasonoi the frictional engagement of the spring. 33; against the periphery of. cam piece 32.

As shown in Figure 8,,the exploring. deyice is mounted. so that with the bar I4. resting. on. the low portion of the cam piece 26., the checking bars 30 and 31- will. freely pass beneath the molded article l6 carried on punches. Biz-without. touching the articles,v but when the bar [4. isresting on the thick portion of cam piece 2-5, as shown in dotted lines in Figure 8, the upperedgeof the bar 30 willengage anyv molded article which is carried by the punch 9a: but will not engagethe punch itself. The arrangementisisuch, that. one checking operation isperformed with the bar on the low part of cam. piece 2.6, and the second checking operation, is performed. after the. cam piece 26: has been moved sothat the bar I4. rests upon. the highpart. of the cam piece. Shifting of the cam piece maybe accomplished in various ways; such asby providing an adjustable stop 34 arranged to engagetheright end of the cam piece 26 near the end of one checking operation to shift the cam piece so. that the bar ldiwill rest on; the low part of the cam, and asimilar adjustable stop. 35: is provided to engage the left. .endof the-cam. 26 near the end of the second; checking operationv to shift the campiece so that the bar l-4-=will rest upon the-high pa-rtofthe cam. Where the rails 25:8;1'6-1110123318 withrespect to the punch plate 9 the steps 34. and 35 will be mountedon a fixed'partof thepress, but where the rails are stationary, and the plate 9 moves with respect to the exploring device, the, stops 3.4. andJE. will be mounted to move with themold plate.

If it be assumedv that the plate 9 is stationary and, the exploring device. moves with respect to the. plate, then the position of the parts as shown in Figure 8 is correct for movement of the exploring device to the left. During such movement, the exploring bars 3|! and 3| will pass freely beneath the caps 6 without touching any of them, and if any are missing, the press will be stopped by means of an electrical device connected with the bar 3| as will be explained hereinafter. After the exploring device passes beyond the last row of punches, the cam piece 26 comes into engagement with stop 35, and stops the movement of the cam piece, while continued movement of rail 25 causes the bar M to ride up to the high part of the cam piece, after which the direction of movement of the rails 25 is reversed for the second checking operation. It will be understood that after the exploring device completes the first checking operation, the ejecting mechanism of the press is operated to eject molded articles from the punches. During the second checking operation when the rails 25 are moving to the right. the checking bar 30 is elevated to a position shown in dotted lines in Figure 8 such that the upper edge of the bar will engage any molded article which remains on any of the punches 9a, and such engagement will cause the bar to be tilted from its normal position so that the flattened portion 32a of the cam piece 32 moves out of a horizontal plane. When the checking device moves to the right beyond the last row of punches, the cam piece 32 passes beneath the operating finger 36a of a normally closed switch 36 which is mounted on a fixed part of the press. If the cam piece 32 is in its normal position, the fiattened portion 32a does not engage the switch operator 36a, but if the bar 39 has been tilted as explained above, the cam piece 32 will engage the part 36a and open the switch 36, thereby interrupting the energizing circuit of the main power switch A.

The arrangement for stopping the press when a molded article is missing from one of the punches during the first checking operation involves an arrangement operating on the same principle as an insulation tester. This involves a transformer 31 having a primary winding 31a connected to a source of current of commercial frequency through a switch 38. This switch is controlled by some moving part of the press so that the transformer is energized during the first checking operation but is de-energized during the second checking operation. In the arrangement shown in Figure 8, this is accomplished by mounting the switch 38 on the bar M in a position such that the normally open contacts of the switch are closed by engagement of the switchoperating plunger 38a with the upper face of rail 25 when the bar I4 is resting on the low part of cam piece 26, but the switch contacts are allowed to open when the bar I4 is resting on the high part of the cam 26.

One terminal of the high voltage secondary winding 31b of transformer 3! is connected to ground through a suitable amplifier 39, and the other terminal is connected to the insulated exploring bar 3|. A relay 40 is connected to the output of amplifier 39, and the armature of this relay normally closes a back contact 40a which is included in the circuit of power switch A in series with switch 36 and a source of current 4|.

The voltage of secondary winding 37b is low enough to prevent any sparking between the insulated bar 3| and any other part of the press when the bar is not positioned beneath a row of punches, but the voltage is suflicient to cause sparking between the bar 3| and any punch which does not have a cap thereon when the bar is located beneath a row of punches. Also, the presence of a cap on any punch will prevent the passage of a spark or discharge between the bar 3] and the punch. Accordingly, during the first checking operation, if all caps are present on the punches, no spark will pass from the bar 3| and relay 40 will remain de-energized. If, however, a cap is missing from one or more punches, a spark or discharge will pass from the bar 3| to the first empty punch, and relay 40 will be energized and thereby pull up its armature and interrupt the circuit of switch A at contact 49a. When the relay 40 is energized, the armature closes a front contact 40b to complete a holding circuit for the relay from the source 4| through a normally closed pushbutton switch 42 and a limiting resistance 43. This holding circuit prevents reclosing of the circuit of switch A until the cause of the improper operation of the press has been removed, and the relay may be restored to normal condition by pressing the pushbutton 42.

While the single insulated bar 3| is employed to explore all of the punches in a given row, the different linear sections of this bar associated with each punch are the equivalent of a plurality of individual exploring elements for the corresponding punches. The same is true of the mechanical checking bar 30. By securely imbedding the lower edge of the bar 3| in the insulating material 301), and by extending the upper edge of this bar above the upper edge of bar 30, the bar 3| may perform both the electrical and mechanical exploring operations.

While the checking devices disclosed herein find their greatest utility in connection with a press having the mold elements arranged in a plurality of parallel rows, it is obvious that these devices will be completely operative where the mold elements are arranged in a single row. Also, the elements need not be arranged in a straight line, but they may be arranged in a staggered row or similar extended array, and the exploring elements would be arranged in a corresponding array so that all of the exploring elements would engage all of the mold elements in the array simultaneously.

As will be seen from the various modifications illustrated in the drawing and described above, my invention is not limited to a particular construction but may have various embodiments, both as to the checking device and the arrangement of the press for utilizing the checking device.

I claim:

1. A device for checking the operation of a molding press having a plurality of mold elements arranged in parallel columns and rows, said device comprising a plurality of feeler elements arranged in a row parallel with the rows of mold elements, one feeler being arranged in line with each column of mold elements, means for producing relative movement between said mold elements and said feelers in a direction parallel with said columns, a relay for stopping said press, means controlled by any of said feelers upon detecting a molded article carried on any of said mold elements tending to operate said relay to stop said press, and means dependent upon the joint control of all of said feeler elements upon detecting molded articles carried by all of the mold elements in any given row for preventing operation of said stopping relay.

2. A device for checking the operation of a molding press having a plurality of mold elements arranged in parallel columns and rows,

grasses 13 said device comprising a plurality of feeler elements arranged in a row parallel with the rows of mold elements, one feeler being arranged in line with each column of mold elements, means for producing relative movement between said mold elements and said feelers in a direction parallel with said columns, means for stopping said press comprising a storage relay having a stepping magnet and a releasing magnet, said relay requiring two successive stepping impulses for stopping said press, means for normallysupplying a stepping current to said relay, means controlled by the operation of any of said feelers upon detecting a molded article carried on any of said mold elements for interrupting said stepping current, and means controlled by the simultaneous operation of all of said feelers upon detecting molded articles carried by all of the mold elements in a. given row for supplyin a releasing impulse to said relay.

3. A device according to claim 2. wherein the circuit for supplying current to the stepping magnet of the storage relay includes a plurality of normally closed switch elements connected in serial circuit relation, and the circuit for supplying current to said releasing magnet includes a plurality of normally open switch elements conin serial. c rcuit ands/her in each of. said feeler devices is arranged upon detecting amolded' article to open one of said normally closed switches and to close one of said normally open switches.

4. A device for checking the operation of a molding press having a plurality of mold elements arranged in a row, said device comprisin a plurality of feeler elements arranged in a row parallel with the row of mold elements, one feeler bein arranged in line with each mold element in said row, means for producing relative movement between said mold elements and said feelers to cause said feeler elements to traverse the row of mold elements, first in one direction and then in the other, a relay for stopping said press, means controlled by the operation of any of said feelers upon detecting a molded article carried on any of said mold elements during the first traverse of said feelers tending to operate said relay to stop said press, means controlled. by the simultaneous operation of all of said feeler elements upon detecting molded articles carried by all of the mold: elements in said row for preventing operation of said stopping relay, means for electing the molded articles from said mold elements, following the first traverse of said feeler' elements,

and means controlled by the operation of any one of said feeler elements during the second traverse of said feeler elements for operating said relay to stop said press.

5. A device for checking the operation of a power driven machine comprising, in combination, a relay for stopping the operation of said machine, a storage relay for controlling the operation of said stoppin relay, said storage relay having a stepping magnet and a releasing magnet and requiring two successive stepping impulses for operating said stoppin relay, a circuit for normally energizing said stepping magnet including a plurality of normally closed switch elements connected in serial circuit relation, a circuit for energizing said releasing magnet including a plurality of normally open switch contacts connected in serial circuit relation, and a plurality of feeler elements responsive to the condition of operation of said machine, each feeler element being arranged upon operation to open one of said nor- ,mol-dadarticles carried thereon,

l4 mally closed switch contacts and to close one of said normally open switch contacts.

.63. A. device for checking the operation, of a power driven machine comprising; in combination, a relay for stopping the operation of said machine, a storage relay for controlling the operation of said stopping relay, said storage relay having a stepping magnet and a releasing magnet and requiring two successive stepping impulses for. operating said stopping relay to a position for stopping said machine, a circuit for normally energizing said stepping magnet, a fce-ler elementresponsive to the condition of operationof said machine, and means controlled by operation of said feeler element for opening the circuit of said stopping magnet and closing the circuit of saidreleasing magnet.

7.11 11 combination, a molding press having a plurality of mold elements arranged in parallel columns and rows, a. checking device comprising a. plurality of feeler elements arranged in a single row parallel. with the rows of mold elements, one feeler being arranged in line with each column of mold elements and serving to detect molded articles carried by said mold elements, means for producing relative movement between said mold elements and said feelers to cause said feelerelements to traverse the columns oi' mold element's first in one direction and then the other, control means responsive to the operation of less than all of said feelers in pass ing a row of mold elements during the first traverse of said feelers to stop said press, means for ei'cc-ting the molded articles from said mold elets following the first traverse of said feeler elements, and said control means being effective upon the operation of any one of said feeler elementsduring the second: traverse of said feeler elements to stop said press.

8. In combination, a molding press having upper and lower mold plates each carrying a plurality of mold element-s, one of said mold plates being movable in and out of said press, an exploring device mounted on and being movable with said movablemol'd. plate for exploring the mold elements carried by the opposite mold plate,

and means controlled by said exploring device orrt'he outward movement of said movable plate for stopping said press if a molded article is missing-trornany ofthe mold elements carried by opposite mold plate, said means being controlled by said, exploring device on the inward moyementzof'saidtmovable plate for stopping said press. if. a. molded article remains on any of the moldgelemen-ts carried-by said opposite plate.

9:. In combination, a molding press having upper and lowerimoldplates each carrying a plurality of mold elements, arranged in parallel columns and rows, means for moving the lower mold plate out of the press and back into the press, a eXplor-ing device mounted on and being movable with said lower mold plate, said exploring device-comprising a plurality of feeler elements arranged in a single row parallel with the rows oigniold elements, one feeler for each column of mold, elements, said feelers being positioned to traverse the columns of mold elements carried by the upper. mold plate and being operated by and control means responsive to the operation of less than all of said feelers in passing a row of mold elements during the outward movement of said lower plate to stop said press, said control means being effective upon the operation of any one of said 15 feeler elements during the return movement of said lower plate to stop said press.

10. In combination, a molding press having a plurality of mold elements arranged in an extended array, a checking device comprising a plurality of feeler elements arranged in a corresponding array parallel with the array of mold elements, one feeler being arranged in line with each mold element in said extended array, means for producing relative movement between said mold elements and said feelers to cause said feeler elements to traverse the array of mold elements first in one direction and then in the other, control means responsive to the operation of less than all of said feelers in passing said array of mold elements during the first traverse of said feelers to stop said press, means for ejecting the molded articles from said mold elements follow ing the first traverse of said feeler elements, and said control means being effective upon the operation of any one of said feeler elements during the second traverse of said feeler elements to stop said press.

11. A device for checking the operation of a power driven machine comprising, in combination, a storage relay having a movable element operable to a position for stopping said machine, said storage relay having a stepping magnet and a releasing magnet and requiring two successive stepping impulses for operating said movable element to stopping position, a circuit for normally energizing said stepping magnet including a plurality of normally closed switch elements connected in serial circuit relation, a circuit for energizing said releasing magnet including a plurality of normally open switch contacts connected in serial circuit relation, and a plurality of movable feeler elements responsive to the condition of operation of said machine, each feeler element being arranged upon operation to open one of said normally closed switch contacts and to close one of said normally open switch contacts.

12. In combination, a molding press having a mold plate carrying a plurality of mold elements,

a carriage mounted to be movable in and out of said press adjacent said mold plate, an exploring device mounted on and being movable with said carriage for exploring the mold elements carried by said mold plate, and means controlled by said exploring device during one direction of movement of said carriage for stopping said press if a molded article is missing from any of the mold elements carried by said mold plate, said means being controlled by said exploring device on the opposite direction of movement of said carriage for stopping said press if a molded article remains on any of the mold elements carried by said mold plate.

13. In combination, a molding press having an upper mold plate carrying a plurality of punches which retain molded articles thereon after each molding cycle, a lower mold plate having a corresponding plurality of die cavities, one of said mold plates being fixed against movement transversely of the press while the other mold plate is movable out of the press transversely thereof, an exploring device mounted in fixed relation with respect to said lower mold plate and in a position to explore the punches on the upper mold plate when said movable plate is moved transversely of said press, and a stopping device controlled by said exploring device during the outward movement of said movable mold plate for stopping said press if a molded article is missing from any of the punches, and means for ejecting the molded articles from said punches, said stopping device being controlled by said exploring'device on the inward movement of said movable plate for stopping said press if a molded article remains on any of said punches.

14. A device for checking the operation of a power driven machine comprising, in combination. means for maintaining the machine in opincluding a pair of closed maintaining contacts, a plurality of exploring devices each including a switch having a pair of upper contacts, a pair of lower contacts, and a movable switch element for selectively bridging either pair of contacts, the upper contacts ofsaid switches being connected in serial circuit relation in one circuit and the lower contacts being connected in circuit relation in another circuit, and relay means controlled by said two circuits and serving to continue said maintaining contacts in closed position so long as said movable switch elements are operated simultaneously from one pair of contacts to another, said relay means being operative upon the movement of less than all of movable switch elements from one position to the other to interrupt said maintaining contacts.

15. A device for checking the operation of a power driven machine comprising, in combination, a plurality of exploring devices each including a switch having a pair of upper contacts, a p r of lower contacts, and a movable bridging element for selectively bridging either pair of contacts, a relay oi the slow-release type, a circuit for energizing the winding of said relay through the upper contacts of said exploring switches connected in serial circuit relation, and a second energizing circuit for the winding of said relay including the lower contacts of said exploring switches connected in serial circuit relation, whereby operation of all of said switch elements from one bridging position to the other simultaneously and within a period less than the time delay period of said relay will prevent the dropout of said relay.

16. A checking device according to claim 15 in which the energizing circuits of said slow-release relay are completed by contacts which are held in closed position by the armature of said relay when the relay is energized, whereby upon release of said armature the relay cannot be re-energized by opration of said checking switches.

' WILLIAM STRAUSS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,257,732 Clark, Jr Oct. 7, 1941 2,371,195 Strauss Mar. 13, 1945 2,350,319 Strauss May 30, 1944 2,356,266 Ogilvie et al Aug. 22, 1944 

